Positive displacement casting

ABSTRACT

Methods and apparatus for positive displacement casting and/or for positive displacement bonding and, more particularly, for automatically forming, on a continuous, reproducible basis, fusion bonds devoid of structural and electrical defects between two or more workpieces by moving a heated electrode into the area to be bonded so as to uniformly heat and melt the portions of the workpieces to be bonded while, at the same time, displacing substantially all of the molten material from the area to be bonded into a storage area or reservoir surrounding the heated electrode where such molten material is maintained in its uniformly heated molten state, and then retracting the electrode so as to permit the molten material to return to the cavity formed by the electrode in the workpieces where such molten material is allowed to cool and solidify, thus forming a flawless bond between the workpieces-thermal or fusion bonds are made in accordance with the methods of the invention and with the apparatus of the invention by a combination of (1) elevated temperature levels sufficient to melt the material to be bonded, and (2) displacement of the molten material; as contrasted with more conventional techniques and/or apparatus which combine elevated temperature levels and pressure.

United States Patent 11 1 Cushman 1 1 POSITIVE DISPLACEMENT CASTING [.75] Inventor: Robert I-Iolbrook Cushman,

Shrewsbury, NJ.

[521 US. Cl 164/80; 29 /204; 136/135 R; 136/168", 164/108; 219/78; 219/86 [51] Int. C15. 1101M 2/22; HOlM 2/30; B23K 1/12;'

' 581 Field of Search ..'.,."164/80, 107, 108, 110,

164/D1G. 7; 29/486, 498, 491, 472.1, 204, 475, 494, 495; 136/176, 134 R, 168; 228/45. 58; 219/78, 86

[56] References Cited UNITED STATES PATENTS 1,066,682 7/1913 Taylor 1,955,438 4/1934 Ragsdale... 2,045,523 6/1936 Fasslcr 2175,314 10/1939 Reynolds 2 69,968 10/1951 Autie et a1 2 703,998 3/1955 Sowter 29/475 3 ,704 2/1966 Rockwell 219/86 3,392,257 7/1968 Glorioso... 2l9/86X 3,626,139 12/1971 Sands ..2l9/86 3,710,435 1/1973 Cordo.... 29/4721 X 3,767,889 10/1973 Sano et a1v 136/134 R X h a? 9 a I flj o a 1 51 Sept. 30, 1975 Primary Eruminor-Francis S. Husar Assistant ErantinerCarl Rowold Attorney, Agent, or FirmWolfe, Hubbard, Leydig, Voit & Osann, Ltd

[57] ABSTRACT Methods and apparatus for positive displacement casting and/or for positive displacement bonding and, more particularly, for automatically forming, on a continuous, reproducible basis, fusion bonds devoid of structural and electrical defects between two or more workpieces by moving a heated electrode into the area to be bonded so as to uniformly heat and melt the portions of the workpieces to be bonded while, at the same time, displacing substantially all of the molten material from the area to be bonded into a storage area or reservoir surrounding the heated electrode where such molten material is maintained in its uniformly heated molten state, and then retracting the electrode so as to permit the molten material to return to the cavity formed by the electrode in the workpieces where such molten material is allowed to cool and solidify, thus forming a flawless bond between the workpieces-thermal or fusion bonds are made in accordance with the methods of the invention and with the apparatus of the invention by a combination of( 1 elevated temperature levels sufficient to melt the material to be bonded, and (2) displacement of the molten material; as contrasted with more conventional techniques and/or apparatus which combine elevated temperature levels and pressure.

29 Claims, 30 Drawing Figures Y II, I 1 I /flZ /Z/' I a! Z/f/W US. Patent Sept. 30,1975 Sheet2of18 3,908,739

US. Patent Sept. 30,1975 Sheet30f 18 3,908,739

II Mung,

US. Patent Sept. 30,1975 Sheet4of18 3,908,739

US. Patent Sept. 30,1975 Sheet6of18 3,908,739

US. Patent Sept. 30,1975 Sheet7ofl8 3,908,739

US. Patent Sept. 30,1975 Sheet80fl8 3,90,739

US. Patent Sept. 30,1975 Sheet90f18 3,908,739

US, Patent Sept. 30,1975 Sheet 10 0f18 3,908,739

US. Patent Sept. 30,1975 Sheet110f18 3,908,739

US. Patent Sept. 30,1975 Sheet 12 of 18 3,908,739

e h S US. Patent Sept. 30,1975

US. Patent Sept. 30,1975 Sheet 14 of 18 3,908,739

Sept. 30,1975 Sheet 15 0f 18 US. Patent QNAEW US. Patent Sept. 30,1975 Sheet 16 of18 3,908,739

1 POSITIVE DISPLACEMENT CASTING RELATED APPLICATIONS Raymond L. Schenk, Jr., Ser. No. 435,178, filed Jan. 21, 1974, Alan S. Keizer, Ser. No. 435,179, filed Jan. 21, 1974.

Robert Holbrook Cushman and Raymond L. Schenk, Jr., Ser. No. 425,169, filed Jan. 14, 1974; Raymond L. Schenk, Jr. and Allan S. Keizer, Ser. No. 435,160, filed Jan. 21, 1974; Raymond L. Schenk, Jr., Robert Holbrook Cushman and Alan S. Keizer, Ser. No. 435,180, filed Jan. 21, 1974; Kurt R. Stirner and Robert Holbrook Cushman, Ser. No. 435,172, filed Jan. 21, 1974; Raymond L. Schenk, Jr. and John A. Bruzas, Ser. No. 435,181, filed Jan. 21, 1972; Raymond L. Schenk, Jr. John A. Bruzas and William E. Coville, Ser. No. 435,182, filed Jan. 21, 1974; John A. Bruzas and William E. Coville, Ser. No. 435,156, filed Jan. 21, 1974; Raymond L. Schenk, Jr. and William B. Hayes, Ser. No. 435,166, filed Jan. 21, 1974;

BACKGROUND OF THE INVENTION The present invention relates in general to fusion casting, and/or to fusion bonding or thermo bonding of two or more workpieces and, more particularly, to methods and apparatus characterized by their ability to automatically form, on a continuous, reproducible, high speed, production-line basis, cast parts having a desired shape, as well as fusion bonds devoid of structural and/or. electrical defects between two or more workpieces by a technique hereinafter referred to as positive displacement casting. It will become apparent as the ensuing description proceeds that the term casting is used herein in its broadest sense and encompasses the melting and shaping or reshaping of one or more parts into a single, unitary structure which may or may not be composite with an unaltered workpiece component, all by and with the positive displacement system disclosed herein. Thus, the phrase positive displacement casting" is intended herein to be generic to positive displacement bonding," In its principal aspects, the invention is concerned with improved methods and apparatus for automatically moving a heated electrode through the portions of the workpiece(s) to be cast or bonded so as to uniformly heat and melt those portions of the predetermined to be cast or bonded While, at the same time, displacing the molten material into a storage area or reservoir surrounding the heated electrode where such material is maintained in its uniformly heated molten state while further movement of the electrode into the workpiece(s) creates a cavity therein and, thereafter, retracting the heated electrode so as to permit the molten material to return to the cavity formed by the electrode in the workpiece(s) where such molten material is allowed to cool and solidify, thus forming a flawless bond between the workpieces and/or casting one or more workpieces in a predetermined shape or form.

in recent years, there has been an ever increasing trend toward, and demand for, automation and mechanization in virtually all branches of industry. In many industries, typically including, but not limited to, the battery making industry, it is often necessary to bond two or more workpieces together to form a unitary assembly wherein the bond is characterized by its strucof electrical conductivity. Various 7 methods have been devised for bonding such workpieces together including, merely by way of example, welding, thermo-compression bonding, ultrasonic bonding, percussion welding, etc.

The particular technique selected has heretofore depended upon many variable parameters, including: 1) the sizes and/or shapes of the workpieces; and (2) various characteristics of the particular materials to be bonded which may vary widely in such areas as electrical and/or thermal conductivity characteristics, melting points, etc. Moreover, the particular technique employed has often been dictated by physical limitations in access to the region where the bonds are to be effected. Merely by way of example, in the battery industry it is often necessary to bond two or more pieces of lead together at various points, in some cases internally and in others externally of a given battery cell. Lead, of course, is characterized by having a relatively low melting point on the order of only 630F., as contrasted with, for example, steel which has a melting point on the order of 3,000F. Moreover, where the lead workpieces comprise battery straps, plates, terminal posts and/or intercell connectors, such as commonly em ployed in industrial motive-power batteries, automotive batteries, and the like, it is often difficult to gain access to the parts to be bonded. Even where access can be obtained, one is normally limited in the amount of heat that can be applied and in the types of reducing agents that can be utilized by virtue of other components present in the area of the bond to be effected such, for example, as the battery casing or cell jar which, in the automotive battery industry, is commonly made of rubber or plastic, and in the industrial motivepower battery industry is normally made of impact resistance rubber; the electrolytic acids present in or to be added to the battery cells; the pasted positive and/or negative plates; the separators which are commonly made of microporous rubber; etc.

Many efforts have been made to devise improved bonding techniques which can be universally applied for the purpose of bonding two or more workpieces together irrespective of the wide range of variable parameters mentioned above. Moreover, consistent with the demands of industry today, numerous efforts have been made to devise bonding techniques which are capable of automation so as to enable automatic bonding of multiple workpieces as an integrated part of massproduction line and/or assembly line techniques. Typical of the aforementioned approaches are those described in US. Pat. Nos. 3,591,755, 3,608,809 and 3,706,126 of Robert Holbrook Cushman, assigned to the Western Electric Company, and relating to mechanical-thermal-pulse continuous fusion bonding processes and apparatus which are based, at least in part, upon a combination of applied and controlled pressure and temperature to effect a desired bond.

However, despite all such prior efforts which have met with varying degrees of success, certain industries have continued to employ the more tedious, timeconsuming, manual bonding techniques which have been known and utilized for many years. Typical of these is the industrial motive-power battery industry where lead-to-lead bonds are still almost universally made by hand-torching or hand-burning techniques employing oxyacetylene torches and/or carbon burning tools. These techniques require highly skilled artisans who are capable of forming satisfactory bonds only 

1. A method of casting meltable material comprising the steps of a. moving a ram relative to the material so as to cause the ram to engage the material; b. establishing a reservoir surrounding the ram and engaged with the material to be cast; c. heating the ram to a temperature sufficient to convert the meltable material in the path of relative ram movement to the molten state; d. moving the heated ram relative to the material and through the reservoir so as to cause the ram to melt the material In its path of relative movement to a desired depth in the material with the molten material thus formed being positively displaced by the ram from the area of ram penetration into the material and shifted therefrom into the reservoir; e. retracting the ram relative to the material from its position of maximum penetration so as to cause the ram to be withdrawn from the material; and, f. returning the molten material theretofore displaced into the reservoir back to the region penetration into the meltable material where such molten material is permitted to cool and solidify.
 2. A method as set forth in claim 1 further characterized in that the reservoir is defined by a barrel having a mold at its lower end surrounding the material to be cast for permitting shaping of the cast part into a configuration defined by the mold cavity.
 3. A method as set forth in claim 2 further characterized in that the barrel is formed of multiple parts separable along parting lines and including the further step of separating said barrel parts following cooling and setting of said material so as to remove the cast part thus formed.
 4. A method of bonding n (where n is equal to two or more) components formed of meltable material together comprising the steps of: a. positioning the n parts on a work axis; b. moving a ram along the work axis relative to the n components so as to cause the ram to engage the n components; c. establishing a reservoir surrounding the ram and engaged with the n components to be bonded; d. heating the ram to a temperature sufficient to convert the meltable material in the path of relative ram movement to the molten state; e. moving the heated ram relative to the n components and through the reservoir so as to cause the ram to melt the material in its path of relative movement to a desired depth in the n components with the molten material thus formed being positively displaced by the ram from the area of ram penetration into the n components and shifted therefrom into the reservoir; f. retracting the ram relative to the n components from its position of maximum penetration so as to cause the ram to be withdrawn from such components; and, g. returning the molten material theretofore displaced into the reservoir back to the area of ram penetration into the n components where such molten material is permitted to cool and solidify, thus creating a molecular fusion bond between said n component which is coextensive with the depth of penetration of the ram into the n components.
 5. The method of bonding n components as set forth in claim 4 further characterized in that said components include an axially projecting lead battery post and a lead intercell connector concentrically mounted about the post, and wherein the reservoir extends coaxially upward from the connector and the ram is moved axially downward through the battery post and through the inner peripheral portion of the connector surrounding the post so as to melt the upstanding portion of the post and the inner peripheral portion of the connector.
 6. A method as set forth in claim 5 further characterized in that the lead battery post projects upwardly through a lead bushing molded in a battery cover and the lead connector is seated on the bushing, and wherein the path of ram movement is coaxial with and through the post so that the ram engages and melts the upper ends of the post and bushing and the inner periphery of the connector.
 7. A method as set forth in claim 5 further characterized in that the ram includes a carbon graphite electrode positioned to engage and melt the lead components in the path of ram movement.
 8. A positive displacement casting apparatus comprising, in combination: a. a surface for supporting meltable workpiece material to be cast; b. a frame; c. a ram carried by said frame for movement relative to the workpiece materiall along an axis coinciding with the ram axis; d. means for heating said ram to a temperatuRe sufficiently high to convert the meltable workpiece material to the molten state upon engagement with said heated ram; e. means defining a reservoir surrounding said ram for receiving the molten material displaced from a cavity formed in the workpiece material during relative axial movement of said heated ram into the workpiece material; f. ram advancing means for positively displacing substantially all of the molten material formed by engagement of said heated ram with the meltable workpiece material into said reservoir defining means surrounding said ram so as to uniformly heat saturate the displaced molten material and to uniformly heat any unmelted portions of the meltable workpiece material adjacent said ram; and, g. means for relatively retracting said ram from engagement with the workpiece material so as to permit the displaced heat saturated molten material confined within said reservoir defining means to return to the cavity formed by the ram in the workpiece material where such molten material is permitted to cool and solidify.
 9. A positive displacement casting apparatus as set forth in claim 8 further characterized in that the workpiece material to be cast comprises multiple component parts, at least one of which is formed of meltable material, and wherein the molten material formed and displaced into said reservoir defining means serves to bond said parts together in a unitary composite assembly.
 10. A positive displacement casting apparatus as set forth in claim 9 further characterizedin that all of said multiple component parts are formed of meltable material and all are positioned, at least in part, on the path of relative axial movement of said ram so that those portions of the meltable component parts disposed in the path of relative movement of said ram will be engaged by said ram, converted to a molten state, and the molten material thus formed will be positively displaced by said ram into said reservoir defining means and, upon retraction of said ram, such molten material will return to the region within said component parts from which it was displaced and will cool and solidify to form a uniform molecular fusion bond therebetween.
 11. A positive displacement casting apparatus as set forth in claim 8 further characterized in that said reservoir defining means comprises a barrel coaxial with and surrounding said ram.
 12. A positive displacement casting apparatus as set forth in claim 11 further characterized in that said barrel is mounted on said frame for movement relative to said ram and for movement relative to the workpiece material to be cast so that said barrel can be bottomed on such workpiece material to define therewith a reservoir and so that relative movement between said ram and said bottomed barrel causes said ram to engage the workpiece material along the path of relative axial ram movement, to melt the material so engaged, and to displace the same into said barrel in surrounding heat transfer relation to said ram.
 13. A positive displacement casting apparatus as set forth in claim 12 further characterized in that means are provided for adjusting the degree of relative axial penetration of said ram into the workpiece material.
 14. A positive displacement casting apparatus as set forth in claim 13 further characterized in that means are provided for terminating relative axial movement between said ram and the workpiece material upon relative penetration of said ram into the workpiece material through a fixed, predetermined axial distance.
 15. A positive displacement casting apparatus as set forth in claim 14 further characterized in that means are provided for establishing a preset dwell period for said heated ram at the limit of its relative axial penetration into said workpiece material so that the molten material in said reservoir defining barrel surrounding said ram is uniformly heat saturated and the unmelted portions of the workpiece material surrounding said ram are uniformly heated.
 16. A positive diSplacement casting apparatus as set forth in claim 11 further including a poer source and characterized in that said ram comprises a resistance-type electrode, said barrel is formed of conductive material, and means are provided for coupling said barrel and said ram to said power source.
 17. A positive displacement casting apparatus as set forth in claim 16 further characterized in that said electrode is formed of carbon graphite.
 18. A positive displacement casting apparatus comprising, in combination: a. a work surface for supporting meltable material to be cast; b. a frame; c. a head assembly carried by said frame with freedom for relative movement towards and away from said surface; d. a ram carried by said head for movement relative to said surface along an axis coinciding with the axis of said ram; e. means for heating said ram to a temperature sufficiently high to convert the material to be cast into the molten state upon engagement with said heated ram; f. means defining a reservoir surrounding said ram for receiving the molten material displaced by said heated ram during relative axial movement of said ram through the material to be cast; g. ram advancing means for positively displacing the molten material formed by engagement of said heated ram with the material into said reservoir defining means; and, h. means for relatively retracting said ram from engagement with the material so as to permit the molten material confined within said reservoir defining means to return to the region from which it was displaced where it may cool and solidify.
 19. A positive displacement casting apparatus of the type set forth in claim 18 further including means for supporting a component element within said reservoir defining means and out of the path of relative movement of said ram through said reservoir defining means so that the molten material formed during relative advance of said ram will at least partially surround the component element upon return to the region from which the molten material was displaced and, upon cooling and solidification, will be cast about such element.
 20. A positive displacement casting apparatus as set forth in claim 18 further characterized in that said reservoir defining means comprises a barrel forming a mold cavity in engagement with said work surface.
 21. A positive displacement casting apparatus as set forth in claim 20 further characterized in that said barrel is formed of multiple parts separable along parting lines.
 22. A positive displacement casting apparatus as set forth in claim 20 further characterized in that said ram includes a bore extending therethrough along the path of relative ram movement, and means are provided for supporting a component element on said work surface and aligned with said bore so that upon relative axial advance of said ram toward said surface said element is received within said bore, and upon relative retraction of said ram the molten material stored in the reservoir defined by said barrel will return to the mold defined by said barrel in surrounding relation to said element when said molten material is permitted to cool and solidify to form a cast shaped composite part having solidified meltable material cast about said element and having an external configuration complementary to the internal shape of said mold.
 23. A positive displacement casting apparatus as set forth in claim 22 further characterized in that said barrel is formed of multiple parts separable along parting lines.
 24. Apparatus for bonding n (where n is equal to two or more) meltable component parts together by a positive displacement molecular fusion bonding process, said apparatus comprising, in combination: a. means for supporting said n meltable component parts on a work axis; b. a frame; c. a bonding head carried by said frame in a position overlying the component parts; d. a barrel carried by said bonding head for movement along said work axis iNto sealing engagement with the component parts to be bonded; e. a ram carried by said bonding head for movement along said work axis, said ram being coaxial with said barrel and capable of axial movement therethrough; f. means for advancing said barrel and said ram into engagement with said component parts; g. means for heating said ram to a temperature sufficiently high to melt and form a cavity in those portions of the component parts in the path of ram movement; h. ram advancing means for positively displacing the molten material formed by engagement of said heated ram with the component parts into said barrel and storing the molten material therein in heat transfer relation with said heated ram; i. means for axially retracting said ram from said component parts so as to enable the displaced molten material stored in said barrel to flow back to said cavity where said material is permitted to cool and solidify to form a uniform molecular fusion bond between said component parts with said bond being coextensive with the degree of penetration of said ram into said component parts; and, j. means for axially retracting said barrel from engagement with said component parts following cooling and solidification of said molten material.
 25. Apparatus as set forth in claim 24 for bonding together n component parts formed of electrically conductive meltable material further characterized in that said barrel is formed of conductive material and said ram includes a resistance-type electrode, said apparatus further including: k. a power source having a pair of terminals; l. means connecting one of said terminals to said electrode and the other of said terminals to said barrel; and, m. a liner positioned within said barrel formed of electrically insulating material; whereby when said barrel and said electrode engage said component parts, a current path is completed from said source through said electrode, said parts and said barrel, said electrode is heated to melt said parts, and said ram and electrode moves downwardly along said work axis with the molten material formed being displaced upwardly into said insulating liner surrounding said electrode.
 26. Apparatus as set forth in claim 24 further characterized in that said electrode is formed of carbon graphite.
 27. Apparatus as set forth in claim 24 further including a fixed stop for limiting axial penetration of said ram into said component parts.
 28. Apparatus as set forth in claim 27 further characterized in that means are provided for adjusting the position of said fixed stop so as to permit controlled adjustment of the degree of penetration of said ram into said component parts.
 29. Apparatus as set forth in claim 27 further characterized in that means are provided for causing said heated ram to dwell at its limit position for a predetermined period prior to activating said means for axially retracting said ram so that the molten material disposed in said barrel is uniformly heat saturated and so that the unmelted portions of said component parts surrounding said ram are uniformly heated. 